mass effect
Displacement or compression of brain structures caused by a space-occupying lesion such as a tumor, hematoma, or abscess.
Full Definition
Mass effect refers to the mechanical displacement of normal brain tissue and structures caused by an expanding intracranial lesion. This phenomenon occurs when tumors, hematomas, abscesses, or other space-occupying lesions grow within the rigid confines of the skull, causing compression of adjacent brain tissue, distortion of ventricular anatomy, and potential midline shift. Mass effect can lead to increased intracranial pressure, herniation syndromes, and focal neurological deficits. The severity depends on the size, location, and rate of growth of the lesion, with rapidly expanding lesions typically causing more severe symptoms than slowly growing ones.
Usage
Usage note: Quantify when possible (e.g., 'mass effect with 5mm midline shift') to convey severity and urgency.
In Context
- "The large frontal tumor demonstrated significant mass effect with 8mm of midline shift requiring urgent surgical decompression." — Emergency neurosurgical consultation